A number of 4-phenyl-4-piperidinecarboxylic acid derivatives have been described in J. Pharm. Pharmacol., 23 (11), 875-876 (1971); J. Med. Chem., 19, 16-19 (1976); and J. Med. Chem., 19, 1248-1250 (1976). These known piperidine derivatives which may be represented by the formula ##STR1## possess analgesic properties.
In Japanese Pat. No. J. 5 3.053.665 there are described a number of 1-(cyclohexyl)-4-phenylpiperidine derivatives which are represented by the formula ##STR2## The latter compounds are taught to be useful as depressants of the central nervous system.
The compounds according to the present invention differ from the aforementioned prior art compounds essentially by the nature of the particular substituents in the 4-position of the piperidine nucleus and/or in the 4-position of the cyclohexyl group.